package Example10.Login;

import java.sql.*;
import java.util.Scanner;

public class Login {
        public static void main(String[] args)  throws SQLException {
            Statement stmt = null;
            ResultSet re = null;
            Connection conn = null;
            try {
                //1. 注册数据库驱动
                Class.forName("com.mysql.cj.jdbc.Driver");
                //2. 通过DriverManager获取数据库连接
                String url =
                        "jdbc:mysql://localhost:3306/jdbc?serverTimezone=GMT%2B8&useSSL=false";
                String username = "root";//数据库账户
                String password = "123456";
                conn = DriverManager.getConnection(url, username, password);
                /**
                 * 终端用户登录
                 *
                 */
                Scanner sc = new Scanner(System.in);
                System.out.println("用户登录");
                System.out.println("请输入你的姓名");
                String userName = sc.next();
                System.out.println("请输入你的密码");
                String userPwd = sc.next();
                String loginSql = "select * from users where name = ? and password = ?";
                PreparedStatement pm = conn.prepareStatement(loginSql);
                pm.setString(1, userName);
                pm.setString(2, userPwd);
                re = pm.executeQuery();//executeQuery返回多行数据 executeUpdate()返回一个int
                //3. 通过Connnection对象获取Statement对象
                stmt = conn.createStatement();
                // 4.使用Statement执行SQL语句
                String sql = "select * from users";
                re = stmt.executeQuery(sql);
                while (re.next()) {
                    int id = re.getInt("id");
                    String name = re.getString("name");
                    if(id>0){
                        System.out.println(name+"登录成功");
                        //如果数据库中有两个同名同密码的人 直接结束循环 只提示第一人
                        break;
                    }
                }
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }finally {
                if ( re  !=null){
                    try {
                        re.close();
                    }catch (SQLException e){
                        e.printStackTrace();
                    }
                    re = null;
                }
                if (stmt!=null){
                    try {
                        stmt.close();
                    }catch (SQLException e){
                        e.printStackTrace();
                    }
                    stmt = null;
                }
                if (conn!=null){
                    try {
                        conn.close();
                    }catch (SQLException e){
                        e.printStackTrace();
                    }
                    conn = null;
                }
            }
        }
    }

